The present invention relates to a method and apparatus by which the actual parameters of a machine's operations can be calculated from theoretical values with the help of models of the drive systems and of the mechanism of the machine.
With the increasing product-quality and economic-efficiency requirements being placed on machine-tool and production-line machine, including robots, the complexity of these machines is constantly increasing. Novel machine kinematics and complex mechanical-electronic functions require greater functional efficiency in the mechanism, drivers and control. However, this is not always easy to design and implement. Because the increasingly urgent need to know the productivity of a machine during the product development process, manufacturers realize that the exact responses of control signals, sensor signals and individual movements, previously used for collision control, provide simulation-supported machine evaluation and optimization. For this purpose, the simulation must replicate the machine's mechanical response and the response of the drivers, as well as the operation of the controller. Only in that way can the response times of the mechanism, the drivers and the digital controller be exactly modeled, for simulating numerically-controlled (NC) operations or tool changing operations, for example.    Different types of models employ different levels of detail in modeling the mechanical response of machine tools at present, for example:    geometric kinematics models that consider only the geometry of the machine's elements, not their masses and elasticities,    equivalence models that consider interconnected functional building blocks, Petri-nets, for example,    rigid many-body systems that consider flexible connecting elements,    multiple-mass models that consider mass and elasticity in the drive train,    flexible many-body systems, and    FE-models with full discretization of the mechanism.
Up to now combinations of the different mechanical models that describe the functions of the control and drive technology in a machine have been limited to particular types of axis elements: only combinations of position-controlled axes, for example.
The article “Virtuelle Werkzeugmaschinen für die Simulation” (Virtual Machine Tools for use in Simulation) in the online journal wt Werkstattstechnik (Workshop Technology), vol. 92 (2002), no. 5, pages 205–209, an operation that applies the coupling of control techniques and simulation systems for various axes is disclosed. Since in that operation the modeling of the drive means is neglected and the desired and actual values are implicitly set to be identical, a realistic representation of the machine's kinematic response to motion cannot be achieved that way.
The article “Echtzeiffähige Maschinenmodelle” (Realtime-capable Machine Model) in the online journal wt Werkstattstechnik (Workshop Technology), vol. 92 (2002), no. 5, pages 187–193, discloses in this connection a drive-model and control-model, as well as a static weight-based model and a dynamic many-body model.
In general, a machine's controller can be integrated into a model used for simulation through a software simulation of the controller. Alternatively, a copy of the original control hardware and its original software can be used by the simulation. A numerical-control (NC) type of controller is essentially a numerical-control kernel (NCK) that guides controlled axes that are NC-operated using combined interpolations, interpolations representing the operation of a control circuit, for example.
In contrast, a programmable logic control (PLC) type of controller generally guides otherwise unregulated axes: a tool changer, for example. However, in the case of one control application, a PLC control unit guides regulated axes and, as a result, PLC-type control can integrate regulated axes using combined interpolations, interpolations for curve tracing for example. Transverse axes and/or conveyor axes are also provided with PLC controllers whether they are regulated or unregulated.
It would therefore be desirable and advantageous to provide an improved realtime-capable machine simulator in which mass and geometrical characteristics of the mechanical components of the machine and their respective drive systems, both regulated or unregulated, are simulated, regardless of whether they are have different types of controllers, while integrating in the simulator all control components.